The present invention relates to a power supply method and a power supply circuit.
As a liquid crystal panel (display panel in a broad sense) used for an electronic instrument such as a portable telephone, a simple matrix type liquid crystal panel and an active matrix type liquid crystal panel using switching elements such as thin film transistors (hereinafter abbreviated as “TFTs”) have been known.
The simple matrix method enables power consumption to be reduced in comparison with the active matrix method. However, it is difficult to increase the number of colors and to display a moving image by using the simple matrix method. The active matrix method is suitable for increasing the number of colors and displaying a moving image. However, it is difficult to reduce power consumption by using the active matrix method.
In recent years, an increase in the number of colors and display of a moving image have been demanded for a portable electronic instrument such as a portable telephone in order to provide a high-quality image. Therefore, an active matrix type liquid crystal panel has been used instead of a conventionally used simple matrix type liquid crystal panel.